Evolution will pay £5m plus the value of the net assets of the business, according to a statement on the London Stock Exchange.

The firm, itself the target of takeover interest from South African banking group Investec, last month said its wealth management arm de Broe was in advanced talks to secure the deal.

De Broë will now take over the private client unit which was previously Fortis Private Investment Management before it was absorbed by the French banking giant.

The acquisition will take the company’s assets under management to £7.8bn, and marks a significant step toward achieving Williams de Broe’s previously stated target of reaching £10bn in assets by 2013.

Ligia Torres, chief executive at BNP Paribas Wealth Management UK, said: “BNP Paribas PIM is an attractive business with experienced staff and I am delighted this transaction has been agreed, allowing for a seamless transfer with minimal disruption to clients.

“This deal allows us to focus on the strengths BNP Paribas Wealth Management can bring to our clients through such an important centre as London and to use its presence here to leverage its key global client network.”